Add Windows build support and instructions

.gitignore

@@ -4,6 +4,8 @@ cmake-build*/
 CMakerLists.txt
 CMakeLists.txt.user
 
+CMakeUserPresets.json
+
 .cache/
 
 .venv/

CMakeLists.txt

@@ -1,7 +1,7 @@
 # This file is automatically generated from cmake.toml - DO NOT EDIT
 # See https://github.com/build-cpp/cmkr for more information
 
-cmake_minimum_required(VERSION 3.18)
+cmake_minimum_required(VERSION 3.27)
 
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
 	message(FATAL_ERROR "In-tree builds are not supported. Run CMake from a separate directory: cmake -B build")
@@ -99,6 +99,14 @@ target_link_libraries(llvm-c-test-vendored PRIVATE
 	LLVM-C-Wrapper
 )
 
+if(NOT TARGET LLVM-Wrapper)
+	message(FATAL_ERROR "Target \"LLVM-Wrapper\" referenced by \"llvm-c-test-vendored\" does not exist!")
+endif()
+
+target_link_libraries(llvm-c-test-vendored PRIVATE
+	LLVM-Wrapper
+)
+
 set_target_properties(llvm-c-test-vendored PROPERTIES
 	OUTPUT_NAME
 		llvm-c-test

README.md

@@ -101,3 +101,73 @@ For development documentation, see `devdocs/README.md`.
 This project is licensed under the MIT License. See [LICENSE](LICENSE) for details.
 
 LLVM is licensed under the Apache License v2.0 with LLVM Exceptions.
+
+## Windows
+
+Download LLVM+Clang:
+
+- https://github.com/vovkos/llvm-package-windows/releases/download/llvm-21.1.1/llvm-21.1.1-windows-amd64-msvc17-msvcrt.7z
+- https://github.com/vovkos/llvm-package-windows/releases/download/clang-20.1.8/clang-20.1.8-windows-amd64-msvc17-msvcrt.7z
+
+Merge them together in `C:\llvm-21.1.1`.
+
+Create `CMakeUserPresets.json`:
+
+```json
+{
+    "version": 3,
+    "configurePresets": [
+        {
+            "name": "clang-cl",
+            "displayName": "Ninja with clang-cl",
+            "generator": "Ninja",
+            "binaryDir": "${sourceDir}/build",
+            "cacheVariables": {
+                "CMAKE_C_COMPILER": "C:/Program Files/LLVM/bin/clang-cl.exe",
+                "CMAKE_CXX_COMPILER": "C:/Program Files/LLVM/bin/clang-cl.exe",
+                "CMAKE_EXPORT_COMPILE_COMMANDS": "ON",
+                "CMAKE_BUILD_TYPE": "RelWithDebInfo",
+                "CMAKE_PREFIX_PATH": "d:/llvm-21.1.1"
+            }
+        }
+    ],
+    "buildPresets": [
+        {
+            "name": "clang-cl",
+            "configurePreset": "clang-cl"
+        }
+    ]
+}
+```
+
+Create a virtual environment:
+
+```bash
+uv venv
+```
+
+Activate the virtual environment:
+
+```bash
+.venv/Scripts/activate
+```
+
+Configure the CMake project (this should find the Python from your venv):
+
+```bash
+cmake --preset clang-cl
+```
+
+_Note_: This saves the LLVM prefix to a file called `.llvm-prefix`, make sure to delete that if you change the LLVM prefix path.
+
+Build the bindings:
+
+```bash
+cmake --build build
+```
+
+After that works you can build the Python package with `uv`:
+
+```bash
+uv sync --verbose
+```

cmake.toml

@@ -1,5 +1,5 @@
 [cmake]
-version = "3.18"
+version = "3.27" # IMPORTED_RUNTIME_ARTIFACTS, $<LIST:FILTER,...>
 cmkr-include = "cmake/cmkr.cmake"
 
 [project]
@@ -39,6 +39,7 @@ type = "test"
 sources = ["llvm-c/llvm-c-test/*.c", "llvm-c/llvm-c-test/*.cpp"]
 headers = ["llvm-c/llvm-c-test/*.h"]
 properties = { OUTPUT_NAME = "llvm-c-test" }
+link-libraries = ["::LLVM-Wrapper"]
 
 # Test targets
 [target.test_context]

cmake/Findnanobind-wrapper.cmake

@@ -72,6 +72,19 @@ function(nanobind_add_typed_module name)
         ${ARGN}
     )
 
+    # Copy runtime DLLs next to the module for testing on Windows
+    # Filter out Python and system DLLs
+    set(dll_filter_regex "python[0-9]*\\.dll|system32|Python[0-9]*/|api-ms-")
+    set(filtered_runtime_dlls $<LIST:FILTER,$<TARGET_RUNTIME_DLLS:${name}>,EXCLUDE,${dll_filter_regex}>)
+    if(WIN32)
+        add_custom_command(
+            TARGET ${name}
+            POST_BUILD
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different ${filtered_runtime_dlls} $<TARGET_FILE_DIR:${name}>
+            COMMAND_EXPAND_LISTS
+        )
+    endif()
+
     # Generate type stubs for the extension module
     nanobind_add_stub(
         ${name}_stub
@@ -100,4 +113,10 @@ function(nanobind_add_typed_module name)
         DESTINATION ${name}
         RENAME __init__.pyi
     )
-endfunction()
+    if(WIN32)
+        install(
+          FILES ${filtered_runtime_dlls}
+          DESTINATION ${name}
+        )
+    endif()
+endfunction()

llvm-bin

@@ -22,7 +22,7 @@ def get_llvm_prefix() -> Path:
 
     with open(prefix_file, "r") as f:
         llvm_prefix = os.path.expanduser(f.read().strip())
-    
+
     path = Path(llvm_prefix)
     if not path.exists():
         print(f"Error: LLVM prefix from .llvm-prefix does not exist: {path}", file=sys.stderr)
@@ -36,6 +36,8 @@ def main():
         sys.exit(1)
 
     tool = sys.argv[1]
+    if sys.platform == "win32":
+        tool += ".exe"
     args = sys.argv[2:]
 
     llvm_prefix = get_llvm_prefix()

pyproject.toml

@@ -45,6 +45,9 @@ cache-keys = [
     { file = "CMakeLists.txt" },
     { file = "src/**/*.cpp" },
     { file = "src/**/*.h" },
+    { file = "llvm-c/llvm-c-test/*.c" },
+    { file = "llvm-c/llvm-c-test/*.cpp" },
+    { file = "llvm-c/llvm-c-test/*.h" },
 ]
 
 [tool.ty.environment]

run_llvm_c_tests.py

@@ -194,6 +194,8 @@ def main():
 
     # Verify required LLVM tools exist
     required_tools = ["llvm-as", "llvm-dis", "FileCheck", "not"]
+    if sys.platform == "win32":
+        required_tools = [tool + ".exe" for tool in required_tools]
     missing_tools = []
     for tool in required_tools:
         if not (llvm_tools_dir / tool).exists():
@@ -224,7 +226,7 @@ def main():
     # Build lit command - use lit from the same venv/environment as this script
     # Try to find lit executable in the same directory as the Python interpreter
     python_dir = Path(sys.executable).parent
-    lit_exe = python_dir / "lit"
+    lit_exe = python_dir / (sys.platform == "win32" and "lit.exe" or "lit")
 
     # Default options: single-threaded, deterministic order
     # User can override with e.g. -j 10 for parallel execution